1. Field of the Invention
The present invention is a trailer or permanently mounted oil dehydrator system for locally produced crude oil. The trailer mounted system can be transported to an oil well site or pipeline stations for use. The permanent system is permanently installed at the appropriate location. The system is designed to remove basic sediment and water (BS&W) from the crude oil prior to the oil being transported from the well site or prior to the oil being introduced into transportation pipelines feeding domestic refineries.
2. Description of the Related Art
Produced crude oil is considered “crude” in that it has not yet been refined. It exists at several hundred thousand individual well sites in the US. This crude oil is often crudely treated at the individual well site in an effort to remove entrained water; however, this effort often falls short. In order to ultimately move all produced crude oil to market, the pipeline crude oil gathering sector accepts this often off-spec crude oil and historically has used only the dilution (blending) process to mask the high concentration of water in a portion of the overall stream prior to shipping the entire blended stream on to the next gathering point via truck transport or pipelines and ultimately into U.S. oil refineries.
Prior to the present invention, pipeline stations used a blending technique to mix crude oil with little or no entrained water with crude oil with up to 10% basic sediment and water (BS&W) to render the mix below 0.5% total BS&W, the typical maximum acceptable by U.S. refiners. Obviously, this blending process required very large quantities of water free crude, so water laden crude oil had to be stored for extended periods in very large tank farms until it could be effectively diluted.
In fact, while the dilution process technically meets the BS&W criteria, it does not remove the water from the crude at all. The refiners must therefore separate the entrained water from their incoming crude oil streams; however diluted the water may be in the crude oil streams. This entrained water represents a serious cost and hazard to refiners, so removing it from the crude oil prior to the oil entering the transportation chain leading to refineries, i.e. crude oil pipelines, is a very significant benefit to the refineries.
Additionally, removing the BS&W at the pipeline stations is a benefit to the pipelines and downstream storage facilities in that the overall volume of transferred crude oil is reduced, thus increasing the net capacity of the pipelines and downstream storage facilities. Those downstream storage facilities include both those along the way to the refineries, such as crude oil storage hubs along the pipeline routes, and those at the refineries where the crude oil is stored in massive tank farms prior to being refined.
Heretofore it there has not been any obvious, economic, or reasonable solution for removing BS&W from the crude oil before it is transported.
Although crude oil dehydration is often attempted to some degree at the points of origin, i.e. at the individual oil well site, that effort is often inefficient. Those attempts at dehydrating the crude oil at the individual oil well site have never embodied the components selected for use in the present invention.
First, low shear pumps are not currently used at well sites. In fact the opposite is true of typical oilfield crude transfer systems. Currently employed typical oilfield crude transfer systems employ high shear pumps. The water droplet shearing characteristics of these high shear pumps agitate and cause increase water-in-oil mixing. Those water droplet shearing characteristics conflict with Stokes' Law separation and ultimately leave larger quantities of water in the crude oil streams.
Second, while some crude is heated at the point of origin to offset the aggravated conditions created by these droplet shearing devices upstream, no effort is made to capture or use any of that heat at the local level, so considerable fuel and related heating energy is wasted. These streams are often shipped to pipeline stations with excessive water concentrations, causing the traditional blending process to be a necessary part of this sector of industry, and creating the need for the present invention.
Finally, the water that is contained in the crude is generally corrosive to metal and any water concentration in the crude presents a significant corrosion potential in both the pipeline equipment and the refinery equipment.
The present invention addresses all of these issues by providing a uniquely efficient crude oil dehydration system designed for local application on oil well sites and pipeline stations where the efficient dehydration of crude oil has its maximum economic benefit to industry by preconditioning the crude prior to transportation to refineries.
The invention combines three benefits: 1) a low shear transfer pump to take fullest advantage of Stokes' Law separation condition, 2) a small, highly efficient heat transfer system to transfer heat from the treated crude oil to the incoming untreated crude oil to preheat the incoming crude oil while cooling the outgoing treated crude oil, and 3) an oil-water separation system designed to preheat the inlet fluid initially, and once pre-heated, to separate small quantities of water from large quantities of crude oil.